Selene is a rather large satellite for a planet, having 27% the diameter and 60% the density of its primary. Thought to have formed 4.5 billion years ago, it is said that Selene was formed when an object the size of Mars collided with Gaea, sending debris into space forming a ring system. The ring system eventually coalesced into the moon.

For thousands of years, humans have used Selene as the basis for their calendar. One revolution by the moon is equivalent to one month by the Gregorian calendar.

In 1969, Human astronauts Neil Armstrong and Buzz Aldrin became the first humans to set foot on a celestial body other than Gaea. This officially marked the moment humanity had entered the early space faring age.

During the War on Gaea, Selene was used as a military supply base, originally owned by the Buyuk Empire, but later captured by Eteno forces. Selene has since become a quiet backwater and producer of helium-3